Phase corrector and phase correction method

Abstract

A phase corrector in a radio transmitter includes a quadrature modulator which modulates a first carrier signal by using an in-phase component and a quadrature component of a first signal, a quadrature demodulator which demodulates a feedback signal by using a second carrier signal to generate a second signal including an in-phase component and a quadrature component, a phase detector which detects a phase error between the first signal and the second signal based on the in-phase components and the quadrature components of the first signal and the second signal, and a phase shifter which performs phase shift of any one of the first signal, the second signal, the first carrier signal and the second carrier signal based on a sum value obtained by adding to the phase error a first phase amount varying on a time base in a given phase range.

1. A phase corrector in a radio transmitter which converts a first signal into a radio signal and amplifies the radio signal by a power amplifier, the phase corrector comprising:
 a quadrature modulator which modulates a first carrier signal by using an in-phase component and a quadrature component of the first signal; 
 a quadrature demodulator which demodulates a feedback signal fed back from an output of the power amplifier by using a second carrier signal to generate a second signal including an in-phase component and a quadrature component; 
 a phase detector which detects a phase error between the first signal and the second signal based on the in-phase components and the quadrature components of the first signal and the second signal; and 
 a phase shifter which performs phase shift of any one of the first signal, the second signal, the first carrier signal and the second carrier signal based on a sum value obtained by adding to the phase error a first phase amount varying on a time base in a given phase range. 
 
     
     
       2. The phase corrector according to  claim 1 , further comprising:
 a correction determining unit which determines whether or not the phase error has been corrected, based on the in-phase components and the quadrature components of the first signal and the second signal, 
 wherein the phase shifter performs phase shift based on the sum value when the correction determining unit determines that the phase error has not been corrected. 
 
     
     
       3. The phase corrector according to  claim 2 , wherein, after the correction determining unit performs determination that the phase error has been corrected, the target value of the phase shifter is obtained by adding to the phase error a second phase amount which is the first phase amount at a time point of the determination. 
     
     
       4. The phase corrector according to  claim 2 , wherein a period during which the first phase amount is added to the phase error, the period starting from a starting time or a time point at which the correction determining unit determines that the phase error has not been corrected, is limited to a given period. 
     
     
       5. The phase corrector according to  claim 1 , wherein the phase detector includes a first memory which stores information on whether a sine value of the phase error is to be increased, decreased or held, according to a combination of digitized signals of components of the first signal and the second signal, and consecutively updates the sine value of the phase error, referring to the first memory based on the components of the first signal and the second signal which are consecutively digitized. 
     
     
       6. A phase correction method in a radio transmitter which converts a first signal into a radio signal and amplifies the radio signal by a power amplifier, the phase correction method comprising:
 modulating a first carrier signal by using an in-phase component and a quadrature component of the first signal; 
 demodulating a feedback signal fed back from an output of the power amplifier by using a second carrier signal to generate a second signal including an in-phase component and a quadrature component; 
 detecting a phase error between the first signal and the second signal based on the in-phase components and the quadrature components of the first signal and the second signal; and 
 performing phase shift of any one of the first signal, the second signal, the first carrier signal and the second carrier signal based on a sum value obtained by adding to the phase error a first phase amount varying on a time base in a given phase range. 
 
     
     
       7. The phase correction method according to  claim 6 , further comprising:
 determining whether or not the phase error has been corrected, based on the in-phase components and the quadrature components of the first signal and the second signal, 
 wherein the performing includes performing phase shift based on the sum value when the determining determines that the phase error has not been corrected. 
 
     
     
       8. The phase correction method according to  claim 7 , wherein, after determination that the phase error has been corrected by the determining, the target value of the phase shifter is obtained by adding to the phase error a second phase amount which is the first phase amount at a time point of the determination. 
     
     
       9. The phase correction method according to  claim 7 , wherein a period during which the first phase amount is added to the phase error, the period starting from a starting time or a time point at which the determining determines that the phase error has not been corrected, is limited to a given period. 
     
     
       10. The phase correction method according to  claim 6 , wherein, the detecting includes updating a sine value of the phase error consecutively with reference to a first memory which stores information on whether the sine value of the phase error is to be increased, decreased or held, according to a combination of digitized signals of components of the first signal and the second signal.